Dynamically Creating Variables

[John Wilkinson]

Hi Guys,
this is my first post and my first real stab at getting to grips with Java. Here's what I'm trying to do:

I have a file that I read line-by-line containing a bunch of User Names and Applications that each User has used. I need a way of counting the number of times each App for any given User has been used. Sounds simple eh? File would look something like this....

User: John
App: Excel
App: Excel
App: Word
App: Outlook
-----------------
User: Fred
App: Word
App: Word
----------------
User: Steven
App: Excel
App: Word

In perl this would be easy. I'd create a Hash Array and dynamically name each key as "User.AppName" (John.Excel, John.Outlook, Fred.Word etc) and then assign each a value based on some counter that i increment, so in the above example, Fred.Word=2. Having read some posts on here and also on other sites, I see that you cannot dynamically create variables in this way. I was wondering if anyone had any ideas as to how I might go about solving this problem..?

Many thanks
Johny

[Steve Luke]

You could use a very similar strategy that you defined above, using a Map (or HashMap). For example:

Map<String, Integer> applicationCounts = new HashMap<String, Integer>();
applicationCounts.put((name+"."+app), count);

[John Wilkinson]

Hi Steve,
I think I may have jumped the gun on this. My explanation was not clear. It's the Application Count that I need a Dynamic Variable for. Once I have that, I can then use a HashMap to store the data, as you suggested. So, in my example file, I would need a way of defining an Int variable unique to each User.App pair - a variable that I increment as and when. Creating the Key is not what I'm after - it's finding a way to store the App count value and increment it...... JohnExcel++ etc
Sorry for any confusion.
John

[Steve Luke]

Oh, sorry

String key = ...
Integer count = applicationCounts.get(key);
if (count == null) //this is the first time this user.app was found
    count = 1;
else //already there?  increment it
    count = count + 1;
applicationCounts.put(key, count);

[John Wilkinson]

You nailed it Steve! Many thanks for your help.
Regards
John